Nature of self-diffusion in two-dimensional fluids
Nature of self-diffusion in two-dimensional fluids
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DOI：
10.1088/1367-2630/aa997d
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发表时间：
2017-09
影响因子：
3.3
通讯作者：
Bongsik Choi;Kyeong Hwan Han;Changho Kim;P. Talkner;A. Kidera;E. Lee
中科院分区：
文献类型：
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作者：
Bongsik Choi;Kyeong Hwan Han;Changho Kim;P. Talkner;A. Kidera;E. Lee
用解析和数值方法研究了二维简单流体中的自扩散问题。我们使用与这些量相关的一致性方程，研究了二维流体中自扩散的异常方面，包括均方位移、与时间相关的扩散系数和速度自相关函数（VACF）。我们数值确认的一致性方程，通过广泛的分子动力学模拟有限系统，证实早期的结果表明，运动粘度接近一个有限的，非零值的热力学极限，并建立有限尺寸的行为的扩散系数。我们得到的热力学极限的一致性方程的精确解，并使用此解决方案来确定大的时间渐近的均方位移，扩散系数，和VACF。VACF的渐近衰减规律类似于先前已知的自洽形式1 /（t ln t），但是具有重新缩放的时间。
Self-diffusion in a two-dimensional simple fluid is investigated by both analytical and numerical means. We investigate the anomalous aspects of self-diffusion in two-dimensional fluids with regards to the mean square displacement, the time-dependent diffusion coefficient, and the velocity autocorrelation function (VACF) using a consistency equation relating these quantities. We numerically confirm the consistency equation by extensive molecular dynamics simulations for finite systems, corroborate earlier results indicating that the kinematic viscosity approaches a finite, non-vanishing value in the thermodynamic limit, and establish the finite size behavior of the diffusion coefficient. We obtain the exact solution of the consistency equation in the thermodynamic limit and use this solution to determine the large time asymptotics of the mean square displacement, the diffusion coefficient, and the VACF. An asymptotic decay law of the VACF resembles the previously known self-consistent form, 1 / ( t ln t ) , however with a rescaled time.